The present invention relates to a system for activating or deactivating an image intensifier tube, or the like, responsive to the reception of optical radiation of increased intensity for the length of time that the optical radiation of increase intensity is being received and to an optical delay circuit for delaying optical radiation of increase intensity until an image intensifier tube is turned on or off.
Image intensifiers have been commonly used in the past for a variety of purposes such as night surveilance by police or by others observing the habits of nocturnal animals or the like. However, such devices can also be utilized in a variety of low light situations, such as when televising ball games, or the like, at night or in low light situations to improve the received signal. One problem with this latter use is the tendency of the image intensifier to be overloaded, thereby damaging the intensifier tube and other circuitry when a bright light is received, such as from a nearby flash blub going off.
The present invention in one of its embodiments is directed toward a system which can momentarily turn an image intensifier or similar circuit on or off momentarily responsive to the reception of optical radiation of increased intensity so as to prevent damage to the image intensifier and related circuitry. In order to accomplish this, a delay circuit is needed to hold the optical signal of increased radiation momentarily while the image intensifier is turned on or turned off. The image intensifier tube could be turned on to record the actual scene when the flash of light goes off in the one embodiment.
Typical prior art patents include U.S. Pat. No. 3,462,603 for a variable delay and beam splitter and U.S. Pat. No. 3,801,819 for fiber-optics in a transmission line used in a laser communication system. In U.S. Pat. No. 3,851,167 a combination image intensifier utilizing a fiber-optics transmission line is provided while in U.S. Pat. No. 3,833,805 an image intensifier is utilized in the laser system. Other patents include U.S. Pat. No. 3,604,936; U.S. Pat. No. 7,733,129; and U.S. Pat. No. 3,877,157.
The present system advantageously allows image intensifier tubes to be utilized in systems in which rapidly changing optically radiation might be received as well as in systems intended to record only short burst of optical radiation of increased intensity.